Evacuable bag

ABSTRACT

An evacuable bag is provided which can prevent any possible contact between laminated sheets so as to achieve a complete deaeration, and can be produced at low cost. Said evacuable bag  10  has a bag main body  1  composed of flexible non-breathable laminated sheets  11 , and provided with an air-outlet  2  which allows the bag main body  1  to communicate with the outside, and a closable opening  3 , the air-outlet  2  permits deaeration of the air in the bag main body  1 , the laminated sheet  11  consists of at least two layers, the outer layer is composed of non-breathable synthetic resin films  12, 13 , and the inner layer is a nonwoven layer formed with a mass of synthetic fibers and unevenness on the surface thereof, at least one part of the synthetic fibers constituting said nonwoven layer has thermoweldability.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to an evacuable bag which is to bedeaerated after it contains an article.

2. Background Art

As disclosed in Japanese publication No. H01-294027, there existed inthe past evacuable bags which have an air outlet formed on the bag mainbody made of flexible synthetic resin for compacting an article such asclothing and beddings in the bag.

To be brief, the way of use comprises putting beddings etc. through anopening into the evacuable bag, then closing the opening by means of asliding fastener, attaching the nozzle of a vacuum to the air outlet tosuck up the air inside the bag, so that the air can be expelled from theoutlet. And then, the evacuable bag can be retained vacuumed by shuttingthe air outlet against incoming air. When the bag containing an articlesuch as clothing and beddings is deaerated, the air within the contentsmay also be sucked out simultaneously. So the size of the package maybecome small as much as the volume has reduced.

In addition to the above purpose, if food such as meats and vegetable aspacked under negative pressure in the evacuable bag is preserved in therefrigerator, it can be protected from spoilage caused by the air in thebag.

Said prior art evacuable bags are made of laminated sheets of syntheticresin film, such as nylon or polyethylene, and partially heat-sealed.

The surface of each laminated sheet is smooth, and when the bag isevacuated, the opposite inner sides of the evacuable bag are broughtinto close contact with each other. However, in deaeration by a vacuum,laminated sheets corresponding to the air outlet in position may partlystick to each other during the process, thus resulting in incompletedeaeration.

In this connection, the above Japanese publication No. H01-294027 hasproposed “TUBULAR CONTAINER”, in which the surface of the syntheticresin films constituting laminated sheets is made uneven by embossingprocess, thereby preventing the laminated sheets from sticking to eachother at the inner side of the evacuable bag. With this prior artcontainer, the laminated sheet has an embossed surface in a checkedpattern, which may avoid contact between the surface of the laminatedsheets to achieve complete deaeration.

However, such a way of making a raised pattern on the surface of thelaminated sheet may cause a high cost of production.

Meanwhile, for the sake of better appearance, there have been laminatedsheets consisting of an embossed sheet with a random pattern called inJapanese “Unryu”, which literally means clouds and dragons, asconventionally used on Japanese paper, and a sheet of synthetic resinfilm. The inventor of the present invention has figured out a way ofusing the uneven surface of said sheet of a Japanese-paper style so asto avoid any possible contact between the laminated sheets.

However, it was found that the Japanese-paper-style sheets were composedof natural fibers, or rayon fibers used in a paper-making process andnot desirable concerning heat-sealing.

Thus, with the uneven surface of the Japanese-paper-style sheets laiddown inside the evacuable bag, the laminated sheets did not beheat-sealed in a bag-making process. In order for theJapanese-paper-style sheets to make hot-sealable, it was necessary tohave the sheet backed with a synthetic resin film like a polyethylenefilm. But, this additional process will result in covering the entiresurface of the Japanese-paper-style sheet with the backing film, wherebythe uneven surface will not appear on the back face of the sheet, onlyto fail an achievement the inventor intends.

In view of this, the object of the present invention is to provide anevacuable bag in which complete deaeration can be carried out with noaccompaniment by any possible contact between the laminated sheets, andthe production process can be performed at a low cost.

SUMMARY OF THE INVENTION

For the purpose of overcoming said problems, a first aspect of thepresent invention provides an evacuable bag having a bag body 1constituted by flexible non-breathable laminated sheets 11, the body 1comprising an air-outlet 2 which permits the body 1 to communicate withthe outside, and a closable opening 3, so that air in the body 1 may beevacuated through said air-outlet 2, wherein the laminated sheets 11consists of at least two layers, of which the outer layer being acombination of non-breathable synthetic resin films 12, 13, the innerlayer a nonwoven layer 14 made of a mass of synthetic fibers, and saidnonwoven layer 14 has thermoweldability.

A second aspect of the present invention provides the evacuable bag asdefined in the first aspect of the present invention, wherein saidnonwoven layer 14 has a ground texture 14 a and islet textures 14 bwhich lie scattered on the ground texture 14 a and arranged in a mannerto rise from the ground texture 14 a, the surface of the nonwoven layer14 is rendered uneven by the ground texture 14 a and islet textures 14b, and at least one cluster of unevenness is formed on the nonwovenlayer 14 in a portion 2 a for air flow located near the air-outlet 2 andin the bags main body 1.

A third aspect of the present invention as defined in the second aspectof the present invention, wherein referring to the unevenness as definedby the ground texture 14 a and islet textures 14 b, the average of thesize difference H between the minimum size of the nonwoven layer 14 inthe ground texture 14 a in the direction of thickness of the nonwovenlayer 14 and the maximum size of the nonwoven layer 14 in the area ofthe islet textures 14 b preferably ranges from 50 microns to 300microns.

A fourth aspect of the present invention as defined in the second aspectof the present invention, wherein the synthetic fibers constituting thenonwoven layer 14 is polyolefin synthetic fibers.

A fifth aspect of the present invention as defined in the fourth aspectof the present invention, wherein the outer layer of the laminated sheet11 consists of nylon film 12 and polyethylene film 13 piled up in thisorder as viewed from the outside of the evacuable bag 10, in thenonwoven layer 14, which is the inner layer of the laminated sheet 11,said ground texture 14 a consists of polyethylene synthetic pulps andpolyethylene-polypropylene conjugate fibers, and the two opposednonwoven layers 14 lying in the inner sides are adhered to each other byheat seal into a bag main body 1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the evacuable bag in accordance with oneembodiment of the present invention.

FIG. 2(A) is a cross sectional diagram showing a laminated sheet of saidevacuable bag. FIG. 2(B) is a perspective diagram showing a nonwovenlayer of said evacuable bag. FIG. 2(C) is a partially enlarged and crosssectional diagram of FIG. 2(B) taken along a line I-I.

FIG. 3 is a diagram showing a specific production process for stocksheet 14 s of the nonwoven layer 14 in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE PREFERABLE EMBODIMENT

The present invention will be described with reference to an embodiment.

An evacuable bag 10 of the present embodiment has a bag main body 1 madeof two plane laminated sheets 11 of a flexible and non-breathablenature, the laminated sheets laid one upon another and being heat-sealedat predetermined section such as the edges, said main body 1 having atight-sealable space to contain an article.

The bag main body 1 includes a closable opening 3, where a fastener 31is disposed for hermetic closure of the opening 3.

The bag main body 1 also includes an air-outlet 2 which admits to theoutside thereof. In the present embodiment, the air-outlet 2 is formedwith a check valve 21. In brief on its structure, the check valve 21 ismade of plane synthetic resin sheets laid one upon another, serving toallow air flow from inside to outside the bag main body 1, whilechecking the air flow in the reverse direction. After an article is putin the bag main body 1 and the opening 3 is closed, the air inside themain body 1 can be manually compressed, or smoothly deaerated from theedge of the bag, which contains the article of a large-sizedconfiguration such as beddings, by using a vacuum to attach the nozzlethereof to the air-outlet 2. And the check valve 21 may check air flowfrom outside the bag to ensure that the bag main body 1 will maintainthe deaerated state.

As shown in FIG. 1, an air passage 22 is formed by heat-sealing thelaminated sheets 11 outside the check valve 21, so the check valve 21will not move outside the evacuable bag 10. However, said air passage 22is not essential to the present invention. It may be omittedaccordingly.

The evacuable bag 10 in accordance with the present invention may not berestricted to the above-mentioned configuration. For example, the bagmain body 1 may be formed by folding a piece of laminated sheet 11. Thevolume of the bag main body 1 may be made larger by providing a gussetat the lateral sides and/or the bottom side. Instead of provision of thecheck valve 21 in the air-outlet 2, closing means such as a cover, tapor fastener may be employed to prevent incoming air from outside the bagmain body 1. Deaeration without the air-outlet 2 may be carried outthrough the opening 3. Or the opening 3 and air-outlet 2 may not belimited to be positioned at the edge of the bag main body 1, may bedisposed on the surface of the main body 1. Thus, the evacuable bag 10of the present invention can be designed in different structures.

As shown in FIG. 2(A), the laminated sheets 11 in the evacuable bag 10in accordance with the present invention are formed integrally bylaminating a plurality of resin films, each of which has appropriatecompositions for specific applications. In the present embodiment, thelaminated sheets 11 are composed of three layers.

The laminated sheets 11 of the embodiment are formed by laminating anylon film 12, a polyethylene film 13, and a nonwoven layer 14 in thisorder. The nonwoven layer 14 is disposed as an inner surface of the bagmain body 1 in forming the bag main body 1.

Although on both inner surfaces of the evacuable bag 10 in thisembodiment are disposed the nonwoven layer 14, the present invention isnot limited to this. It may be arranged only on either inner surface.

The nonwoven layer 14 consists of synthetic fibers. In this embodiment,the synthetic fibers used here are polyethylene synthetic pulps andpolyethylene-polypropylene conjugate fibers. The synthetic fibers shouldnot be restricted to the abovementioned articles, and choice may be madeof a variety of compositions. However, at least one of the syntheticsmust be thermoweldable. For example, polyolefin synthetic fibers may beapplicable. Incidentally, polyolefin is chain hydrocarbon having adouble bond, and means polymer as formed by addition of polymerizationof olefins, which is shown in its general formula CnH2n, such asethylene (C2H4), propylene (C3H6), and buthylene (C4H8). In thisembodiment, the respective different fibers are bonded by thermofusingof part of polyethylene among said synthetic fibers.

Forming process of the nonwoven layer 14 is to join said syntheticfibers together into a sheet-like web, and fuse some of the syntheticfibers with thermoweldability, polyethylene in this case, by heatingsaid web into an integrated sheet.

In this embodiment, the nonwoven layer 14 has a ground texture 14 a andislet textures 14 b. The islet textures are arranged to lie scattered onthe ground texture 14 a, or the arrangement may be so-called“island-in-the-sea” arrangement. The ground texture 14 a is relativelyof a fine texture, consisting of polyethylene synthetic pulps andpolyethylene-polypropylene conjugate fibers, while the islet texture 14b is relatively of a coarse texture, consisting ofpolyethylene-polypropylene conjugate fibers. This is because the islettexture 14 b is composed of synthetic fibers gathered into a singlesolid of high density.

Having thus arranged, the nonwoven layer 14 presents a random patternresembling an old Japanese design called “Unryu”, which literally means“clouds and dragons” in appearance. By varying the islet textures 14 binto different shapes, the diversity of patterns other than the aboveUnryu pattern can be obtained.

The use of the synthetic fibers tinged with pigment may create colorfulnonwoven layer 14. In the present embodiment, titanium oxide has beenapplied to the polyethylene-polypropylene conjugate fibers, therebytaking white color. Furthermore, ornaments such as metallic foil ortinged resin pieces may lie scattered together with islet textures 14 bon the ground texture 14 a in such a manner that they will not be theleast inconvenience at the time when the unwoven fabric is heated.

Now, a production method for stock sheet 14 s of the nonwoven layer 14in accordance with the present invention will be explained specificallywith reference with FIG. 3 by way of example.

The polyethylene-polypropylene conjugate fibers comprising the groundtexture 14 a (hereinafter called “fiber A”) has a structure composed ofa sheath portion made of polyethylene and a core portion ofpolypropylene, a single fiber being 3.3 decitex (dtex) in thickness and15 millimeter (mm) in length.

The polyethylene-polypropylene conjugate fibers consisting of the islettextures 14 b (hereinafter called “fiber B”) has a structure composed ofa sheath portion made of polyethylene and a core portion ofpolypropylene and a single fiber being 3.3 dtex in thickness and 25 mmin length.

Referring to the components constituting the nonwoven layer 14 of thepresent embodiment, the weight ratio of polyethylene pulps (hereafterreferred to as “pulp”), fiber A, and fiber B is respectively 40%, 50%,and 10%.

The size of single fibers for fibers A, B is not restricted to theabovementioned. The thickness may be 1 to 7 dtex, preferably 2 to 4dtex, and the length 10 mm to 20 mm for fiber A, and 20 mm to 30 mm forfiber B.

A web 14W, a layer-like aggregate of the pulps and the fibers, isproduced by a process using a round net.

In this process, pulps and fiber A are at first agitated in the waterwithin a first agitating tank 21. The pulps are subjected to beatingbefore introduced into the first agitating tank 21 so as to facilitatesubsequent intertwining of pulp fibers.

On the other hand, fiber B and a sticking agent are agitated in a secondagitating tank 22 into an aggregate of fibers which is to become islettextures 14 b. For production of conventional type of unwoven fabricusing rayon fibers, said aggregate could easily be formed merely byagitating rayon fibers and a sticking agent. However, since it isdifficult for olefin fibers like fiber B of this embodiment to aggregatethemselves in the level of fiber unit, it is impossible to make anaggregate of fibers by the production method applicable for rayon fiberaggregate. In this connection, prior to mixing with a sticking agent,fiber B is soaked in an anchoring agent so as to facilitate itscoherence, and then, agitated together with the sticking agent until thefiber aggregate has been formed.

Then, the pulps and fiber A as agitated in the first agitating tank 21and the aggregate of fiber B as agitated in the second agitating tank 22are mixed together, and introduced into a tank 23. The pulps, fiber A,and fiber B are taken with the round net 14 now in rotary motion asdisposed within the tank 23, and then, transferred to felt 25 sliding asit keeps in contact with the round net 24, thereby forming a web 14W.The round net 24 is a cylindrical object defined by a metallic net withvery small meshes.

The resultant web 14W is conveyed to a dryer 26. The dryer 26 here usedis a so-called Yankee Dryer, which serves to dry the web 14W moving on aheated roller.

The dried web 14W is then transferred to a heat suction unit 27. In thisproduction process, heated air 27, which is lower than the melting pointof polypropylene in the core portion of the fibers A, B, and higher thanthat of polyethylene in the sheath portion of the pulps and the fibersA, B, specifically 100° C. to 150° C. at the temperature, is transmittedthrough the web 14W, whereby some portion of polyethylene in the pulpsand the fibers A, B of the web 14W will melt. This may cause the pulpsand fibers A, B to join together into a stock sheet 14 s.

As the entire stock sheet 14 s thus produced is composed of olefinsynthetic fibers, it is heat-sealable unlike the conventionalJapanese-paper-style sheet using natural fibers or rayon fibers.Therefore, the nonwoven layer 14 can be attached on the inner surface ofthe evacuable bag 10. Additionally, it is not necessary to have saidstock sheet 14 s backed by synthetic resin like polyethylene, as hasbeen practiced in the past. This may help cost-reduction on theproduction.

In addition to the abovementioned, referring to a matter of severance,fusion cutting was not applicable to the conventionalJapanese-paper-style sheet, and the only cutting way ended up in acutter. However, the stock sheet 14 s of polyolefin constituting thenonwoven layer 14 of the present invention can be fusion-cut. Thereforecan be selected the optimum severance for each of specific productionprocesses, which may help reduce production cost.

Furthermore, as a secondary effect due to the provision of the nonwovenlayer 14 with an appearance of the Unryu pattern of aJapanese-paper-style, the evacuable bag 10 having an excellentappearance is provided.

As illustrated in FIG. 1(B), the islet textures 14 b of the nonwovenlayer 14 lie scattered on the ground texture 14 a, and in FIG. 2(C)which is a cross sectional view, at least some of the islet textures 14b are arranged as if they float in the ground texture 14 a. The islettextures 14 b rise from the surface of the ground texture 14 a, whichrenders the surface of the nonwoven layer 14 uneven. This unevennessdepends upon the state of the synthetic fibers constituting the islettextures 14 b, and the degree of “protrusion” of the islet textures 14 bfrom the surface of the ground texture 14 a, so that though it is notuniform as a whole, the average value of the size difference H betweenthe minimum size of the nonwoven layer 14 on the ground texture 14 a inthe direction of thickness of he nonwoven layer 14 and the maximum sizeof the nonwoven layer 14 in the area of the islet textures 14 bpreferably ranges from 50 microns to 300 microns.

And the nonwoven layer 14 is stuck on the synthetic resin films 12, 13in a fashion to lie on top until a laminated sheet has been formed,then, a bag main body 1 is formed by the nonwoven layer 14 arranged asan inner layer in the inner surface thereof.

In case of the conventional evacuable bags as made of laminated sheetswith smooth surface, the areas of the laminated sheets in the positioncorresponding to the air-outlet were inclined to closely contact witheach other in deaeration, thereby leading to incompletion. However, withthe evacuable bag 10 in accordance with the present invention, bothinner surfaces of the body 1 of the evacuable bag 10 are composed ofnonwoven layers 14 with the surfaces rendered uneven by the groundtexture 14 a and islet textures 14 b, so that the inner surfaces may beimmune from undesirable contact to ensure the suitable maintenance ofinterspaces which permit air flow in any event. In deaeration the air inthe bag main body 1 can be easily led to the air-outlet 2 and ensurecomplete deaeration.

It will be noted that at least one cluster of unevenness is formed onthe nonwoven layer 14 in a portion 2 a for air flow located near theair-outlet 2 in the bag main body 1. This region 2 a may be wide enoughto prevent any subsequent contact between the laminated sheets 11 and tosecure an air passage to the air-outlet 2, specifically, the range ofthe region 2 a shall be within 50 mm from the air-outlet 2 (in thepresent embodiment, the internal open end 21 a of the check valve 21).

It will also be noted that the formation of the islet textures 14 b isnot essential in the present invention. Even if the nonwoven layer 14has been formed only by the ground texture 14 a, as the ground texture14 a itself is made of synthetic fibers twisted together, it has anuneven surface, which may afford an effect similar to theabove-mentioned.

In the case of the production of the nonwoven layer 14 can be used theknown production process for general nonwovens just as it is, such as apaper-making process, carding process, air-lay process, spanbondprocess, or melt-blow process. The foregoing process using the round netis a kind of the paper-making process. Therefore, as compared with theprior art method of rendering uneven the surfaces of the synthetic resinfilm constituting the laminated sheet as disclosed by the aforementionedpatent publication, the production can be conducted at much lower cost.

This particular evacuable bag 10 is most suitable for use in bulkyobjects as impregnated with air, such as beddings, articles of clothing,and foods which may spoil by air contact, as meat, vegetables. It iswell adabtable to other different objects without limitation to theabove-mentioned.

When in use, the evacuable bag 10 always can retain an interspace foradmitting air flow which may arise from the fact that the laminatedsheets 11 will never stick to each other because both inner sides of thebody 1 of the evacuable bag 10 are constituted by nonwoven layers 14with uneven surface. Thus, during evacuation, air within the bog body 1is smoothly led to the air-outlet 2 to ensure complete deaeration.

Additionally, for the production of the nonwoven layer 14 can be usedthe known production process for the general nonwovens, such as apaper-making process, carding process, air-lay process, spanbondprocess, or melt-blow process just as it is. Therefore, as compared withthe conventional method of rendering uneven the surfaces of thesynthetic resin films consisting the laminated sheets, production can beperformed at much lower cost.

Unlike the conventional Japanese-paper-style sheets containing naturalfibers or rayon fibers, the sheets of the present invention can beheat-sealed into a bag main body, and moreover, the backing process forsynthetic resin, as polyethylene, for rendering the sheets heat-sealableis not necessary, which may help cut production cost accordingly.

Additionally, because the nonwoven layer 14 looks like Japanese paper inappearance, the evacuable bag has an excellent appearance.

1. An evacuable bag having a bag main body constituted by flexiblenon-breathable laminated sheets, the bag main body comprising anair-outlet which permits the bag main body to communicate with theoutside, and a closable opening, so that air subsisting within the bagmain body may be evacuated through said air-outlet, wherein thelaminated sheets consists of at least two layers, of which the outerlayer is a combination of non-breathable synthetic resin films, theinner layer is a nonwoven layer made of a mass of synthetic fibers, andsaid nonwoven layer has thermoweldability.
 2. The evacuable bag asdefined in claim 1, wherein said nonwoven layer has a ground texture andislet textures which lie scattered on the ground texture and arranged ina manner to rise from the ground texture, the surface of the nonwovenlayer is rendered uneven by the ground texture and islet textures, andat least one cluster of unevenness is formed on the unwoven layer in aportion for air flow located near the air-outlet in the bag main body.3. The evacuable bag as defined in claim 2, wherein, referring to theunevenness as formed by the ground texture and islet textures, theaverage of the size difference H between the minimum size of thenonwoven layer in the ground texture in the direction of thickness ofthe nonwoven layer and the maximum size of the nonwoven layer in thearea of the islet textures preferably ranges from 50 microns to 300microns.
 4. The evacuable bag as defined in claim 2, wherein thesynthetic fibers constituting the nonwoven layer is polyolefin syntheticfibers.
 5. The evacuable bag as defined in claim 4, wherein that theouter layer of the laminated sheet consists of nylon film andpolyethylene film piled up in this order as viewed from the outside ofthe evacuable bag, in the nonwoven layer, the inner layer of thelaminated sheet, said ground texture consists of polyethylene syntheticpulps and polyethylene-polypropylenes conjugate fibers, and said islettexture consists of polyethylene-polypropylene conjugate fibers and thetwo opposed nonwoven layers lying in the inner side are adhered to eachother by heat-seal into a bag main body.